Magnetic separating process and apparatus



J P. BETHKE ANDR. H. STEARNS. MAGNETIC SEPARATING PROCESS AND APPARATUS.

APPLICATION FILED JUNE 1 I, 1919.

Patented Apr. 25, 1922.

4 SHEETS-SHEET l.

awuentoz J. P. BET HKE AND R. H. STEARNS. MAGNETIC SEPARATING PROCESSAND APPARATUS. 4

APPLICATION FILED jUNEH. 1919.

Patented Apr. 25, 1922. A

SHtEl'S-SHEET 2" 1y: '5.

I A ayumntoz .l. P. BETHKE AND R. H.'STEARNS.

Patented Apr. 25, 1922.

4 SHtEI'S-SHEET 3.

(him an J P. BETHKE AND R. H. STEARNS. MAGNETIC SEPARATING PROCESS ANDAPPARATUS- APPLICATION FILED JUNEH, I919.

' Patented Apr. 25, 1922.

4 SHkEIS-SHEET 4.

clrrowe 1 lures STATES AENT OFFICE.

JOHN P. IBETHKE AND ROSWELL H. STEARNS, or MILWAUKEE, Wisconsin.

MAGNETIC SEPARA'IING PRDCESSAND APPARATUS.

Application filed June 11,

To all whom it may concern:

Be it known that we, JOHN P. Barium and ROSWELL H. STEARNS, citizens ofthe United States, residin at Milwaukee, county of Milwaukee, an Stateof VVisconsin, have invented new and useful Improvements in MagneticSeparating Processes and Apparatus, of which the following is aspecification.

Our invention relates to improvements in magnetic separating processesand apparatus.

The object of our invention is to provide Ine'ansfor utilizin 'analternating current to subject mechanlcally moving magnetizable materialto a pulsating magnetic pull, i. e., to provide a magnetic field o-fulsating or varying intensity in which the e. ect upon the material issimilar to that which would result from a pulsating direct currentwithout change of polarity, and to pass the material through such afield under the influence of gravity or upon an apron which supports andactuates it while allowing the material to readjust itself under theinfluence of successive waves of magnetic energy which cause the'magnetizable particles to shake out or release entrained non-magneticparticles, and allow them to be delivered separately.

Our invention is adaptable to substantially all common typesof'mag'netic separators by reconstruction of the magnet as hereinafterset forth, in order that an alternat-I ing electrical current may beused, in the manner and for the purposes described' In the drawings.

Figure 1-is a side view, partly in longitudinal section, of a magneticseparator drum provided with an interior alternating current magnetembodying our invention in its preferred form, and showing the windingsconnected with a source of alternating current supply.

Figure 2 is a cross sectional view of the same taken on line 2-2 ofFigurel.

Figure 3 is a sectional view on line 3-3 of Figure 2 with arrowsindicating the direction of current flow in the windings.

Figure 4 is a similar view to Fig. 2 on a reduced scale, with a feedinghopper and delivery spout in assembled relation to the Specification ofLetters Patent. Patented Apr, 25, 1922.

1919. Serial No. 303,423.

drum and with the energizing coils omitted to more clearly show the formof the pole pieces.

Figure 5 is a similar view showing a slight modification.

Figure 6 is a similar view illustrating conventionally theuse of ourinvention in a separator of the endless belt and pulley type.

Figure 7 is a conventional side elevation of a drum separator of theaxially inclined, interior. feed type, with our invention appliedthereto.

Figure 8 is an end view of the same on .line 88 of Figu T he process.

Our improved process is based upon the discovery that instead ofutilizing the alternating current to provide a travelingelectro-magnetic field which will progressively draw the magnetite outof the path along which the. nonmagnetic materials trave either bygravity or by means of a. conveyor, such a current can be utilized todevelop a field in which the effect upon the material is the same as apulsating stationary field, in which the magnetic pulsations in eachpole piece are sufficiently rapid notwithstanding the fact that when thecurrent reverses and takes a direction opposite to that taken when thepolarity was initially established, so that the particles of material donot have time p material, the low intensity may be so quickly followedby the next high intensity wave or pulsation as to prevent the magneticmaterial from discharging with that which is non-magnetic, and" theslight movements which develop in the magnetic material during the lowintensity period are instantly followed by a quick jerky movementas theparticles are re-arranged under the influence of the recurring strongpull of the highly energized pole.

For example, it is plainly observable in our improved process that atthe crest of the" high intensity ,wave, elongated particles tend tostand on end upon a conveyor which sup-. ports-them above the polepiece, or in some cases, where they are of sufficient length,

they tend to bridge the gap between the pole pieces. But in thesucceeding period of low 0 intensity the up ended particles tend to fallover, and the bridging particles tend to be pushed along by thenon-magnetic material or other conveying force, out of bridgingposition. Then, when the current again reverses and restores theintensity of the field,

I the particles snap back into the same or new positions of energeticretention, and all of these movements are very effective in shaking outentrained non-magnetic material.

We findthat this principle can be utilized in a great variety of waystoefi'ect a cleaner separation than is possible to accomplish withdirect current separators. The volume of'current, required is somewhatgreater, but this is a negligible factor, since the' totalcurrentconsumption is small, and efficient separation is the primaryconsideration.

We have also discovered that by our imroved process it is possible totemporarily at least impart dia-magnetic'qualiti'es to certain metals,such for example. as aluminum preferably extending transversely totheenergizing ,winding. be of such frequency as to prevent any fallingparticles of magnetite from acquiring" and its alloys-and we utilizethis fact also in promoting the desired separation.

material through an electromagnetic field having parallel poles ofopposite polarity path alongwhich the'material travels, and we rapidlyvary the intensity of the field by passing an alternatin current throughthe he alternations should material momentum. We support the materialupon a mechanically actuated conveyor or set of conveyors which travelin such a,- manner as to tend to mechanically carry-the magnetite inone'direction while either car- .ryin-g the non-magnetic material inanother direction or allowing it' to .drop by gravity away from themagnetite. By utilizing the pulsating magnetic pull due to the varyingenergy of the pole pieces, and by also utilizing-the agitation in theparticles thereby produced .and by further utilizing the diamagneticvforce developed as above described, all inconnection with mechanlcalmeans for urging the magnetite out of the magneticfield in the directionof its desired delivery,

In carrying out our process, we pass the a more thorough separation maybe accomplished than was heretofore believed possible.

Our process is further explained in the following description ofapparatus adaptable for our purposes.

Apparatus.

Referring to Figures 1, 2, 3 and 4, it will be observed that thematerial is fed from a hopper 1 through a chute 2' over the upwardlymoving side of a drum, the peripheral wall 3 of which is lapped ate,with the outer margin forming a longitudinally extending shoulder 6facing in the direction of drum rotation.

A stationary shaft 8 supports the dr and is provided with a set ofsegmental brackets 9' within the drum which support an arcuate-magnetcomposed of laminated plates disposed in a. longitudinally e extendingseries and arranged to form a base 11 and parallel pole pieces 12 and13.

The conductor windings 14;. and 15 extend longitudinally in the channelsbetween .the pole pieces and obliquely across the ends of the polepieces as clearly shown in Figure 2, there being two superposed setsofwindings in each channel, and the conductors of the inner ,set beingextended obliquely across the pole piece ends and 'sufiicient for ourpurposes.

Fan blades 17 preferably secured to one or both end walls-of the drum,are adapted 'to deliver currents of air through the drum andparticularly the gapbetween the magnetic poles and the drum, and alsothrough the spaces between the bracket arms. Thorough ventilation isdesirable for the reason that considerable heat is generated when thecurrent is working in oppositidn to the magnetic flux as hereinafterexplained,'and

unless good ventilation is secured, or the heat otherwise disposed of,the efliciency .of

the separator will be impaired. {The drum I maybe actuated from anysuitable source of power, by meansof a sprocket wheel or pulley 20, anda chain or belt 21..

It will be observed in Figure lthat the hopper or chute2 is providedwithan end wall 25 which extends below the bottom,

with a small gap at 26 between it and the bottom wall. The "end wall 25is adapted to check the momentum of the material sliding down throughthe chute 2 from the hopper 1, and 'todirect this material in a slowlymoving stream against the surface of the drum at a point opposite themagnet.

In the construction shown in Figures 1, 2, 3 and 4, the magnet issupported by the shaft 8 within the upper half of the drum on theupwardly moving side, and the directing feed wall delivers the materialto the drum a little below the longitudinal center line of. the magnet.The non-magnetic material slides down the face of the drum until itreaches a point where it can drop vertically to the ground, or into asuitable receptacle 30. The magnetizable material tends to remain infixed relation to the nearest pole piece, but it is brought into contactwith the moving surface of the drum, the friction of which tends tocarry it upwardly and over-the top of the drum, as indicated by theupper exterior arrow in Figure 4.

On the other hand, after each reversal in the direction of the currentwhich tends to neutralize the magnet, the material tends to 1' drop bygravity in the direction taken by the non-magnetic material. Some of themagnetite will move slightly in that direction before the next reversalin the direction of the current restores the intensity of the field.Therefore, under the influence of the drum friction and the pulsatingmagnetic pull, the particles of magnetizablematerial will be in almostconstant motion. Some of these particles will adhere to the drumsufiiciently to be carried upwardly from pole to pole to the top of thedrum. But if the drum is smooth surfaced, many of the particles willremain in substantially the same position with reference to the magnet,although in continuous vibration, until the shoulder 6 comes in contactwith them, and pushes them upwardly over the to of the drum, and beyondthe magnetic fie d, after which they are allowed to drop into a receiver27. J

If the drum is not smooth surfaced, its friction may be foundsufficientto effect the delivery of the magnetizable material into thereceiver 27. But where the surface of the drum is smooth, it willusually be found necessary in this type of separator to employ some formof rib or projection, such as the longitudinally extending shoulder 6.

In Figure 5, the drum 3 revolves in the.

direction indicated by the interior arrow. The magnet is in all respectsthe same as that illustrated in Figures 1, 2, 3, and 4, except inlocation. The hopper 1, chute 2, and d1- recting wall 25 may besubstantlally the same in structure and arrangement.

But it will be observed that the magnet is located largely in the lowerquadrant of the drum on the descending side, the uppermost pole 13 beinglocated substantially opposite the outlet 26 of the chute 2 In this formof construction, the non-magnetic sand and other material dropsvertically in and dro 'afint'o the receiver provided for such material.In Figure 6, the drum 3 constitutes one member of a 'set of pulleys orrollers 3 and 40, about which a belt or apron 41, composed ofnon-magnetizable material,

is adapted to travel. In this construction a hopper 1 can be directlyprovided with an outlet 26", which discharges upon the horizontallymoving portion of the apron 41 in any suitable manner, the aproncarrying the material in the direction indicated by' the interior arrow,and ultimately passing through the magnetic field withinthe pulley 3 Inthis construction the non-magnetic material drops into the bin 30", andthe magnetizable material into the bin 27". I

In Figures 7 and 8, a drum 3 is employed, this drum being supported uponan inclined shaft 8, and the material to be separated being fed into thedrum through a hopper 1. This drum revolves as indicated by the interiorarrow in Figure 8, thereby constantly serving as a mechanical elew'atorto progressively lift material on the upwardly moving side of the druminto a magnetic field established by an exterior electro-magnet having abase 11, and having arcuate pole pieces 12 and 13 extendingsubstantially from the lower side of the drum to the upper side, withthe ends of the pole pieces approximately in a vertical plane which1ncludes the drum axis. material follows the pole pieces to the upperend thereof, whereupon it is carried over and beyond the magnetic fielduntil it drops into a chute 45, projecting outwardly from the lower endof the drum, and delivers the magnetizable material to a suitable pointof discharge.

It will be observed in Figures 8 and 9 that the laminations in this formof construction constitute the core portion of the magnet, the coilcovers and base being formed of separate arcuate strips of material.

In Figures 10 and 11, the hopper 1 is associated with a conveyor belt orapron 41 running over pulleys 40 and 42 in substantially the same manneras in Figure 6. but the magnet is located above the central portion ofthe apron 41, with its pole pieces 12 and 13 projecting downwardly intoproximity to the apron 41 with an auxiliary transversely moving apron 5Ointerposed. This apron 50 is arranged to run over rollers 51 and 52. asbest shown in Figure 11. In this form of construction the energizingcoil is wound about the depending legs of the magnet, the lower ends ofwhich legs conduced magnet, composed of a magnetizable \bar 54,extending transversely of the apron 41, along the underside of the upperp.or-

tion of said apron, and spanning the gap between the \pole pieces 12 and13 whereby the lines of force of the magnetic field will pass throughthe apron in substantially a direction, allowin terial to passcontmuously out of the field,

vertical direction.

It will be understood that the Various forms of construction illustratedin the drawings, differ from the direct current magnetic separators incommon use principally by having the core members and pole pieceslaminated, i-. e., composed of a series of fiat plates havingmagnetizable material secured together in any suitable manner, such, forexample, as. the bolts or rivets 55, shown in Figure 9; also in the factthat the windings in each case extend longitudinally around the polepieces. The arrangement is such that the pole pieces will alternate. butthe current in adjacent windings will always flow in the same directionbetween adjacent pole pieces.

Further, a higher degree of heat absorption will be required, and instructures where the surface of thecarrier is smooth,

and its movement is across the pole pieces, it will be found necessary,or at least desirable, to provide means whereby the carrier maymechanically engage the magnetizable material, and carry it out of themagnetic field, either continuously or periodically,

It will of-course be understood that while I have only indicated analternating current generator 60 in the Figure 1 with conductors 61, 62and 63 (the generator illustrated being a three phase generator) leadingfrom the generator to the windings through a suitable passage in theshaft 8, each of the several forms of construction illustrated, is to beconnected with a similar source of alternating current forenergizing themagnets.

We claim 1. The method of separating magnetic from non-magneticmaterials, COIlSiStiIlg in passing the mixed material into anelectromagnetic field, periodically reversing the direction of theenergizing current to produce cycles of varying magnetic intensity andthe non-magnetic maand mechanically removing .the magnetized materialfrom the field independently of agitation due to saidcurrent reversals.

' 2. The method of separating magnetic from non-magnetic material,consisting in passing the mixed material into an electromagneticfieldhaving energizing windings through which an alterating current ispassing, subjecting the magnetizable material to a succession of thevariations in the intensity and direction of the field derived from thereversals of the energizing current, allowing the non-magnetic materialto pass freely out of the field in one direction, and mechanicallyrenfoving-the magnetized material in another direction while it is beingsubjectedto said pulsating magnetic attraction.

3. The method of separating magnetic from non-magnetic material,consisting in utilizing an alternating current to provide a magneticfield having polar members of varying polarity with rapidly varyingintensity, mechanically conveying the mixed material in a thin streamthrough themagnetic field in proximity to said polar members,'magnetically supporting the magnetizable material in opposition togravity, and mechanically conveying it, while so supported, in

a different direction from that taken by the non-magnetic material,while partially releasing the magnetizable material at rapidly recurringintervals of low intensity, to allow shifting movements of the particlesunder the influence of gravity followed by forcible rearrangementsthereof due to the successive reversals of magnetic polarity.

4:. An alternating current magnetic separator, including the combinationof aset of laminated pole pieces, polyphase windings'thereon to provideadjacent pole pieces of opposite polarity, a conveyor traversing themagnetic field of said pole pieces, and adapted to receive the pressureof the magnetized material while allowing the non magnetic material todrop by gravity therefrom, means for distributing mixed material to theconveyor; and means for supplying an alternating current to said coils.

5. An alternating current magnetic separator, including the combinationof a revolving conveyor, an arcuate electro-ma net having laminated polepleces, polyp ase windings thereon to provide adjacent pole pieces ofopposite polarity extending along lines transverse to the line ofconveyormovement, and in proximity to one side of the conveyor, meansfor feeding material to the other side of the conveyor,.a nd means forpassing an alternating current through the energizing coils to produce amagnetic field of varying intensity, said conveyor being adapted tosupport magnetized material in said field in a position to allow thenonmagnetic material to drop "away from it while the remaining-materialis being vibrated by the. variations in magnetic flux.

6. An alternating current magnetic separator, including the combinationof a revolving conveyor, an arcuate electro-mag net having laminatedpole pieces provided with energizing coils wound to provide adjacentpole pieces of opposite polarity, ex-

tending along lines transverse to the line.

' ing material is being vibrated by the variations in magnetic flux, andsaid conveyor being provided with means for mechanically engaging themagnetized material to push it along the line of conveyor movement to asuitable point of delivery.

7. In an alternating current magnetic separator, the combination of aset of laminated parallel pole pieces arranged with in- -terveningchannels to receive energlzing coils, and two sets of windings in eachchannel, arranged with those of one set extending around one pole pieceand those of the other set extending around another pole piece, andmeans for passing an alternating current through the sets of coils.

8. In an alternating current magnetic separator, the combination of aset of laminated parallel pole pieces arranged with intervening channelsto receive energizing coils, and two Sets ofsuperposed Windings in eachchannel, arranged With those of one set extending around one pole pieceand those of the other set extending around another pole piece, meansfor passing an alternating current through the sets of coils, saidwindings being passed obliquely across the ends of the pole pieceswhereby the coil having one portion at the base of a channelis disposedin the next channel in superposed relation to the next coil.

In testimony whereof we aflix our signatures in the presence of twowitnesses. JOHN P. BETHKE.

ROSWELL H. STEARNS. Witnesses:

O. C. WEBER, A. J. MCKERIHAN.

